Set small data pointer on PowerPC

[Joakim Tjernlund]

On Sun, 2007-03-18 at 17:48 +0000, Joseph S. Myers wrote:
> On PowerPC, r13 is used for a small data pointer and needs to be set up 
> from _SDA_BASE_ (defined by the linker) at startup.
> 
> This is needed for the GCC testcase gcc.target/powerpc/980827-1.c to work.  
> This patch fixes that testcase (verified for both static and dynamic 
> linking).

I have been thinking about this myself on and off, but since nobody has
complained until now I didn't do anything about it.

Curious, do you use SDA for any real work or do you know of
any such use?

 Jocke

> 
> Index: libc/sysdeps/linux/powerpc/crt1.S
> ===================================================================
> --- libc/sysdeps/linux/powerpc/crt1.S	(revision 18137)
> +++ libc/sysdeps/linux/powerpc/crt1.S	(working copy)
> @@ -58,6 +58,13 @@
>  	mflr	r31
>  # endif
>  #endif
> +	/* Set up the small data pointer in r13.  */
> +#ifdef __PIC__
> +	lwz	r13,_SDA_BASE_ at got(r31)
> +#else
> +	lis	r13,_SDA_BASE_ at ha
> +	addi	r13,r13,_SDA_BASE_ at l
> +#endif
>  	/* Set up an initial stack frame, and clear the LR.  */
>  	li	r0,0
>  	stwu	r1,-16(r1)
>